Idiom: "horsing around"
Mariela: Minami, you really should pay more attention in your Idioms class. I don’t think you pay attention in class, you are always horsing around.
Minami: Horsing around? I don’t have a horse! I don’t even know how to ride a horse. I take the bus everywhere I go!
Mariela: No, silly. Horsing around means goofing around and not paying attention.
Minami: Okay, you are right. I really need to stop chatting with Bruno and Sylvia in Idioms class and need to start paying attention to what the teacher says.
Meaning: "horsing around" means to be goofing around, playing around. Not paying attention.